3
\$\begingroup\$

I make a mistake in my design before getting several PCBs printed and I now need to fix it.

I missed a connection between two areas. Connection needs to carry 3amps peak at a low duty cycle.

Board is 2 layer, 2oz copper.

I can either connect pads about 10mm away, or I’m wondering about connecting traces. I have a 2mm gap between the two areas that’s about 5mm long with nothing between.

Is there an easy way to remove the solder mask, expose the copper on both sides and make a good connection? Would scraping away the mask and getting a blob of solder on there work?

\$\endgroup\$

2 Answers 2

7
\$\begingroup\$

I have fixed similar situations by doing what you suggest. Gently remove the solder mask on both areas and connect them with a blob of solder. Ideally I place it under a microscope and use a sharp knife to scrape of the solder mask, avoiding damaging the copper .

It might be a help to use a small piece of solid wire across the gap to help the solder make a connection and not just get sucked to each side of each area.

The solder will easily carry the current as it is a lot thicker than your copper traces.

\$\endgroup\$
4
  • \$\begingroup\$ Thanks. Will give that a try! \$\endgroup\$
    – Simm
    Apr 19, 2020 at 9:46
  • 1
    \$\begingroup\$ For scraping, I suggest a slightly curved blade, such as Swann Morton 10. If you use a straight blade like a 10a it's difficult to get it flat over the solder mask. \$\endgroup\$
    – jonathanjo
    Apr 19, 2020 at 10:21
  • \$\begingroup\$ End of a flat head screwdriver also works to scrape off the solder mask. It tends to chip it off rather than cutting so minimised damage to the copper. \$\endgroup\$ Apr 19, 2020 at 10:23
  • 1
    \$\begingroup\$ Given the small area I found using a hypodermic needle (25G) worked best. I did try a scalpel but the needle was much better at just going underneath the solder mask and not risking cutting the copper. \$\endgroup\$
    – Simm
    Apr 19, 2020 at 17:46
2
\$\begingroup\$

I use "solder wick" copper-stranded-flat-braided material, for both its intended purpose and for creating heavy structures such as Grounds, VDDs , and jumpers as needed.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.